Small refactoring of modules/private (#15947)

* Use correct variable name.

* doer is never nil here.

* Use status code constants.

* Replaced generic map with concrete struct.

* Fixed windows lint.

* Removed unused method.

* Changed error codes.

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/private/hook.go

@@ -54,7 +54,7 @@ type HookOptions struct {
 	GitAlternativeObjectDirectories string
 	GitQuarantinePath               string
 	GitPushOptions                  GitPushOptions
-	ProtectedBranchID               int64
+	PullRequestID                   int64
 	IsDeployKey                     bool
 }